1. Field of the Invention
The present invention is directed to an anchor for use in a friable material, particularly to a self-drilling anchor for use in drywall.
2. Description of the Related Art
Because drywall is a friable material, mounting articles thereto can be difficult. In the past, self-drilling anchors have been used. However, self-drilling anchors have been known to achieve a pull-out strength of only about 50 to 70 pounds.
Some prior “splitting” anchors of this general type require a high installation torque for the internal fastener. If the friable surface is excessively hard, the anchor may break during the drywall installation. Also, some current anchors cause drywall to blister around the head, wobble during drilling, and/or offer a poor fit for Phillips drivers. In use, in some current “splitting” anchors, the head does not seat flush or below the drywall surface, and may experience cracking in the area around the Phillips recess. Moreover, most current “splitting” anchor products do not have a thread that, in use, wedges the anchor to the back face of the dry wall, and does not grip an optimal amount of the drywall material.
For heavier loads, toggle bolts have been used. Toggle bolts have been known to be expensive, unreliable and difficult to install because they typically are not self-drilling. In addition, toggle bolts and other heavier duty anchors generally have multiple mechanical steps that occur hidden behind the drywall surface after the fastener head is flush with the head of the anchor, a bar needs to flip and tighten against the back of the drywall, anchor plastic material needs to be knotted up or knurled against the back of the drywall, or a metal “umbrella” stricture needs to be collapsed against the back of the wall, e.g. Because users may believe installation is complete once the fastener is flush with the anchor head, they may not perform these additional steps, resulting in incomplete installation, which may lead to failure of the anchor and damage to mounted property.
Attempts have been made to create self-drilling anchors that are easier to install than toggle bolts, are more reliable than toggle bolts, and generate increased pull-out strength over other self-drilling anchors. While they represent an increase over previous self-drilling anchors, they still exhibit lower strength than toggle bolts. What is needed is an anchor for a friable material that overcomes shortcomings of prior art anchors and provides benefits over toggle bolts and other existing anchors.